Supervisory signal for telephone-switchboards.



No. 683,480. I Patented Oct. I, I9Ul. F; R. MBBE RTY & J. L. McflUARRIE. SUPERVISORY SIGNAL FOBTELEPHUNE SWITCHBOABDS.

(Application filed Aug. 19, 1898.)

(No Model.)

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NITED STATES PATENT OFFICE.

FRANK R. MCBERTY, OF EVANSTON, AND JAMES L. MCQUARRIE, OF

CHICAGO, ILLINOIS, ASSIGNORS TO THE WESTERN ELECTRIC COM- PANY, OF CHICAGO, ILLINOIS.

SUPERVISORY SIGNAL FOR TELEPHONE-SWITCHBOARDS.

SPECIFICATION forming part of Letters Patent No. 683,480, dated October 1, 1901.

Application filed August 19, 1898- berial NO. 689025. (No model.)

To all whom it may concern:

Be it known that we, FRANK R. MOBERTY, residing at Evanston, and JAMES L. MOQUAR- RIE, residing at Chicago, in the county of Cook and State .of Illinois, have invented a certain new and useful Improvement in Supervisory Signals for Telephone Switchboards, (Cases Nos. 74 to 77,) of which the following is a full, clear, concise, and exact description.

This invention concerns the operation of electromagnetic supervisory signals temporarily associated with telephone-lines in telephone-switchboards and controlled automatically in the use of the telephones of the lines through the agency of the telephoneswitches at the stations.

The object of the invention is to permit the use of such signals indiii'erently with grounded lines or metallic lines or metallic lines having permanent ground connections.

In certain classes of telephone-lines, notably metallic part-y-lines provided with selective signals, it has been found desirable to place signaling appliances in permanent ground branches from the limbs of the metallic circuits. The link conductors for interconnecting lines in the switchboard must be provided with a battery in a ground branch therefrom and with a supervisory signal in the path of current from the battery to a line with which the link conductors are tempo rarily associated in order that they may be used in uniting grounded lines provided at their stations with grounded return-conductors closed only during the use of the telephone. This requirement precludes the use of plug-circuits of usual type with grounded metallic circuits, since on such circuits permanent grounds exist, furnishing a path for the current through the supervisory signal without respect to the operation of the telephone-switch.

Prior to our invention it has been proposed to place a relay in each of the two conductors of a plug-circuit-one the direct and the other the return conductor of a complete metallic circuit-and to control a supervisory lamp associated .with the link conductors through the agency of a circuit which must be simultaneously closed or opened at both relays to effect the illumination of the signal. Our invention is based on the same principle of operation, but is applied to electromagnetic signals which are operated directly through the ageucyot current flowing in the lines.

Our invention consists in the combination, with the link conductors, of an electromagnetic signal in the path of current to one of the line conductors of a grounded metallic circuit with which the link conductor may be associated, a relay in the path of current to the other line conductor, a single source of current in the link conductors adapted to traverse in series the electromagnets of both these appliances, the circuit thereof being controlled at the substation through a tele phone-switch closing a bridge of the line in the use of the telephone, and circuit connections of the relay with the electromagnetic signal, whereby the relay controls and modifies the action of the signal.

The invention is illustrated in the attached drawing and may be described in detailwith reference thereto.

The drawing represents diagrammatically two telephone-lines of usual equipment for the operation of automatic signals, with a single pair of plugs and their associated plugcircuit for uniting lines in a switchboard, the plug-circuit being provided with ourimproved supervising apparatus. One of the lines represented is a metallic-circuit party-line havingground branches and the other is agrounded line.

The equipment of the substation may comprise the usual polarized call-bells, telephone receivers and transmitters, and telephoneswitches, the telephonic appliances being arranged for utilizing current in the line-circuit to excite the transmitters. The polarized hell I) of the station A is placed in a ground branch from the line conductor 1, leading to that station, together with a condenser. The bell at the station A is interposed in a permanent ground branch from one line conductor 3 of the metallic circuit leading to that station, while the bell at the other station A is similarly disposed in the ground branch from line conductor 2 metallic circuit.

Conductor 1 from station A is led to a spring-jack c in a telephone-switchboard, and thence, having traversed the switch-contacts of the spring-jack through the winding of an electromagnetic line-signal d, to the free of the same pole of a grounded battery e, which is com- 5 Obviously the same pair of plugs must be utilized for uniting grounded lines or metallic-circuit lines or party-lines or any two of these different classes while maintaining a uniform mode of operation of the supervisory signals for the guidance of the operator. These plugs form the terminals of conductors 4. and 5,Which constitute the plug-circuit. The windings of a repeating-coil g are interposed in the conductors in the usual manner for effecting a conductive separation of the two plugs, and a battery It is placed in a bridge of the plug-circuit formed between the windings of this repeating-coil for supplying current to excite the substation-transmitters and to work the signals.

The plug-circuit is furnished with the usual opcrators listening-key (not shown) and with two callingkeys It and each adapted to operate the bell at one of the stations A or A and A The conductor 5 of the plug-circuit, which terminates in the sleeves of the two plugs f and f, is designed to unite those line conductors which terminate in the longer springs c in the spring-jacks-namely, the line conductors 1 of the grounded lines and the conductors 2 of the metallic circuits. The electromagnets of two supervisory signals Z and Z are interposed in the conductor 5 of the plug-circuit, one between each plug and the central bridge-battery 72., so as to be in the path of current from the battery to a line with which the corresponding plug may be connected.

The apparatus hereinbefore described is of well-known arrangement and operation. Ob-

. viously it such appliances be used in uniting grounded lines or metallic circuits current pervisory signals Z and Z to the respective stations with which they are connected as long as the telephones at those stations are removed from their hooks, and such current will be interrupted when the telephones are replaced on their switch-hooks in virtue of the condensers which are brought into the line-circuits in the movement of the telephoneswi'tches; but if such a plug-circuit be associated with a metallic circuit having permanent grounds, as with the party-line to stations A and A current will flow continuously from battery It through the grounds at the stations of the party-line, which will continuously maintain the excited condition of the supervisory signal and render it ineffective.

In applying our invention we further associate with the plug-circuit two relays m and m, which are interposed in conductor 4 of the plug-circuit, one at each side of the central bridge. These relays, which are in the path of current in the return limbs of metallic circuits, control the action of the supervisory signals Z and Z, respectively. Thus that portion of the conductor 5 which includes the signal Z is controlled by the switch-contacts of relay 'm, being closed when the relay is excited, while the similar portion of the conductor 5 extending between the repeating coil g and the plug f is controlled by the switch-contacts of the relay m. The supervisory signals Z and Z, together with the relay-contacts which control them, are permanently shunted by non-inductive resistancecoils n and a, respectively, in the usual way, for the purpose of cutting out the resistance of the magnet-windings with respect to telephone-currents.

- To render the signals Z and Z operative when associated with grounded lines, the relays m and m must obviously be excited. To this end,the portions of the spring-jacks of grounded lines which are ordinarily connected directly to ground are in this instance connected with the free pole of the grounded battery 6.

In the use of the apparatus here described the subscribers call consists merely in the removal of the telephone at the substation for use. This act on the part of the subscriber permitsthe telephone-switch to close a bridge of the line-circuit, whether the line be a grounded line or a metallic line or a grounded metallic party-line. The current thus produced in the line from the battery 6 causes the display of theline-signalof the callingline. The call is answered by the insertion of the answering-plugf in the spring-jack of the calling-line in the usual way. Having learned the subscribers order, the operator completes the required connection andrings the bell at the station wanted by means of a suitable key 76 or k. Thereafter she supervises the connection by means of signals Z and Z, which by their display indicate the re- I placement of the telephones on their switchhooks. will flow from the battery it through the su- In the case of a signal Z, associated with a grounded line, as shown in the figure, the controlling-relay m becomes excited by current flowing from the battery e through a portion of conductor 4 of the plug-circuit and through one Winding of the repeatingcoil g to earth. The relay closes the portion of conductor 5, including the signalZ, which is thus brought into the path of current from battery h to the line-conductorl and thence to earth at the substation. The continuity of this path is controlled by the telephone-switch at the substation A. Hence the supervisory signal Z, by its hidden or displayed condition, indicates the position of the telephone-switch at station A.

In the case of the grounded metallic partyline current flows in the first instance from battery it through the resistance-coil n to line conductor2. From that conductor, when the circuit is complete through the telephone at any station, the current returns through line conductor 3 and finds circuit to the conductor 4 of the plug-circuit, and thus through relay we back to battery h. The relay closes its switch-contacts together, and thus completes the circuit through the supervisory signal Z, whereby the concealment of the signal is eifected. If the bridge at the station of the party-line where the telephone is in use should be broken by the replacement of the telephone on its switch, the relay m would be deprived of current and wonldthus break the circuit through the supervisory signal Z and bring about the display of its target. This function is obviously exercised without interference from ground branches on either of the line conductors 2 or 3.

If connection were made with a metallic circuit by means of either of the plugs, the signal and relay would operate in accordance with the mode just traced for metallic partylines. Thus the uniform operation of the signals Z and Z would be maintained without respect to the nature of the lines, which are connected through the agency of the plugs and plug-circuit.

Our invention is defined in the following claims:

1. lhe combination with the line conductors of a telephone-line, a source of current in the line and a switch for closing the circuit of the line, of an electromagnetic signal in one conductor of the'line and a relay in the other conductor of the line controlling the said signal, as described.

2. The combination with two limbs of a metallic telephone-line, a source of current connected with the line, a switch at thestation of the line controlling the continuity of the circuit, of an electromagneticsignal in one limb of the line-circuit in the path of current from said source to the substation, and a relay in the other limb thereof, in the path of said relay being in the path of current from said source to the substation and being controlled by the switch at the station, and circuit connections controlled by the relay determining the [low of current in the said sig nal, as described.

4. The combination wit-h a metallic telephone-circuit having ground branches from its conductors, a switch at the substation for closing the line-circuit, a source of current in a ground branch from one conductor of the line, a resistance-coil in the same conductor of the line, an electromagnetic supervisory signal in shunt of the resistance-coil, and a relay in the other conductor of the line-circuit, said relay having switch-contacts adapted, when excited, to complete the circuit of the shunt including said electromagnetic signal, substantially as described.

5. The combination with grounded telephone-lines with switches at the stations thereof for closing groundbranches of the lines, grounded metallic circuits and switches at the stations thereof for closing bridges of the lines, and spring-jacks forming terminals of the lines in a switchboard, of double link conductors for uniting the lines, a ground branch from that conductor of said link conductors designed to unite the line-wires of grounded circuits and a source of current therein, and a ground branch from the other link conductor, a supervisory signal in one of the link conductors anda relay controlling the current through the signal in the other link conductor, substantially as described.

6. The combination with grounded telephone lines with switches at the stations thereof for closing ground branches of the grounded metallic circuits and switches at the stations thereof for closing bridges of the lines, and spring-jacks forming terminals of the lines in a switchboard, of double link conductors for uniting the lines, a ground branch from that conductor of said link conductors designed to unite the linewires of grounded circuits and a source of current therein, a ground branch from the other link conductor, a supervisory signal in one of the link conductors and a relay controlling the current through the signal in the other link conductor, and means for producing current in the directly-grounded link conductor when associated with a grounded line, as described.

7. The combination with grounded telephone-lines with switches at their stations for closing the circuits thereof in the use of the telephones, metallic-circuit telephone-lines having grounded line conductors and switches at the stations thereof for closing normally open bridges of the lines in the use of the telephones, and spring jacks forming the terminals of said lines in the switchboard, of plugs and a plug-circuit for uniting lines, a ground connection with that conductor of the plug-circuit designed to unite line-wires of grounded lines, a source of current in the ground branch therefrom, and an electr0- magnetic supervisory signal in the said conductor of the plug-circuit, a ground branch from the otherconductor of the plug-circuit, and arelay in the said conductor, said relay controlling the circuit through said supervisory signal, and means permanently associated with the grounded lines for exciting the said relay when connection is made with a grounded line; whereby the signals are caused to operate in a uniform manner with grounded lines and with-grounded metallic circuits, as described.

8. The combination with a telephoneline and a telephone-switch for closing the normally broken line-circuit during the use of the telephone, of a spring-jack terminal for the line, a plug and plug-circuit adapted to make connection therewith, a source of current in the plug-circuit controlled by the switch at the substation of the line, a supervisory signal in the plug-circuit, in the path of current from said source to the substation, a relay controlling the circuit of said signal, and a circuit containing the magnet of said relay, closed in making connection with the line, as described. v

9. The combination with telephone-lines and a plug and plug-circuit for making connection with them, the stations of said lines having switches controlling the continuity of the lines, of a source of current connected with the plug-circuit, a supervisory signal in the path of current therefrom to the substation, a relay controlling the circuit of said supervisory signal, circuit connections of said relay adapted to excite the relay when connection is made with a line, to render the signal operative, said circuit connections of the relay being controlled by the telephoneswitch of the metallic line-circuit, as described.

In witness whereof we hereunto subscribe our names this 27th day of July, A. D. 1898.

FRANK R. MOBERTY. JAMES L. MCQUARRIE. Witnesses:

ELLA EDLER, MYRTA F. GREEN. 

